export function getMtlLoader(THREE) {
  /**
 * Loads a Wavefront .mtl file specifying materials
 *
 * @author angelxuanchang
 */
  function MTLLoader(manager) {

    THREE.Loader.call(this, manager);

  };

  MTLLoader.prototype = Object.assign(Object.create(THREE.Loader.prototype), {

    constructor: MTLLoader,

    /**
     * Loads and parses a MTL asset from a URL.
     *
     * @param {String} url - URL to the MTL file.
     * @param {Function} [onLoad] - Callback invoked with the loaded object.
     * @param {Function} [onProgress] - Callback for download progress.
     * @param {Function} [onError] - Callback for download errors.
     *
     * @see setPath setResourcePath
     *
     * @note In order for relative texture references to resolve correctly
     * you must call setResourcePath() explicitly prior to load.
     */
    load: function (url, onLoad, onProgress, onError) {

      var scope = this;

      var path = (this.path === '') ? THREE.LoaderUtils.extractUrlBase(url) : this.path;

      var loader = new THREE.FileLoader(this.manager);
      loader.setPath(this.path);
      loader.load(url, function (text) {

        onLoad(scope.parse(text, path));

      }, onProgress, onError);

    },

    setMaterialOptions: function (value) {

      this.materialOptions = value;
      return this;

    },

    /**
     * Parses a MTL file.
     *
     * @param {String} text - Content of MTL file
     * @return {THREE.MTLLoader.MaterialCreator}
     *
     * @see setPath setResourcePath
     *
     * @note In order for relative texture references to resolve correctly
     * you must call setResourcePath() explicitly prior to parse.
     */
    parse: function (text, path) {

      var lines = text.split('\n');
      var info = {};
      var delimiter_pattern = /\s+/;
      var materialsInfo = {};

      for (var i = 0; i < lines.length; i++) {

        var line = lines[i];
        line = line.trim();

        if (line.length === 0 || line.charAt(0) === '#') {

          // Blank line or comment ignore
          continue;

        }

        var pos = line.indexOf(' ');

        var key = (pos >= 0) ? line.substring(0, pos) : line;
        key = key.toLowerCase();

        var value = (pos >= 0) ? line.substring(pos + 1) : '';
        value = value.trim();

        if (key === 'newmtl') {

          // New material

          info = { name: value };
          materialsInfo[value] = info;

        } else {

          if (key === 'ka' || key === 'kd' || key === 'ks' || key === 'ke') {

            var ss = value.split(delimiter_pattern, 3);
            info[key] = [parseFloat(ss[0]), parseFloat(ss[1]), parseFloat(ss[2])];

          } else {

            info[key] = value;

          }

        }

      }

      var materialCreator = new MTLLoader.MaterialCreator(this.resourcePath || path, this.materialOptions);
      materialCreator.setCrossOrigin(this.crossOrigin);
      materialCreator.setManager(this.manager);
      materialCreator.setMaterials(materialsInfo);
      return materialCreator;

    }

  });

  /**
   * Create a new THREE.MTLLoader.MaterialCreator
   * @param baseUrl - Url relative to which textures are loaded
   * @param options - Set of options on how to construct the materials
   *                  side: Which side to apply the material
   *                        THREE.FrontSide (default), THREE.BackSide, THREE.DoubleSide
   *                  wrap: What type of wrapping to apply for textures
   *                        THREE.RepeatWrapping (default), THREE.ClampToEdgeWrapping, THREE.MirroredRepeatWrapping
   *                  normalizeRGB: RGBs need to be normalized to 0-1 from 0-255
   *                                Default: false, assumed to be already normalized
   *                  ignoreZeroRGBs: Ignore values of RGBs (Ka,Kd,Ks) that are all 0's
   *                                  Default: false
   * @constructor
   */

  MTLLoader.MaterialCreator = function (baseUrl, options) {

    this.baseUrl = baseUrl || '';
    this.options = options;
    this.materialsInfo = {};
    this.materials = {};
    this.materialsArray = [];
    this.nameLookup = {};

    this.side = (this.options && this.options.side) ? this.options.side : THREE.FrontSide;
    this.wrap = (this.options && this.options.wrap) ? this.options.wrap : THREE.RepeatWrapping;

  };

  MTLLoader.MaterialCreator.prototype = {

    constructor: MTLLoader.MaterialCreator,

    crossOrigin: 'anonymous',

    setCrossOrigin: function (value) {

      this.crossOrigin = value;
      return this;

    },

    setManager: function (value) {

      this.manager = value;

    },

    setMaterials: function (materialsInfo) {

      this.materialsInfo = this.convert(materialsInfo);
      this.materials = {};
      this.materialsArray = [];
      this.nameLookup = {};

    },

    convert: function (materialsInfo) {

      if (!this.options) return materialsInfo;

      var converted = {};

      for (var mn in materialsInfo) {

        // Convert materials info into normalized form based on options

        var mat = materialsInfo[mn];

        var covmat = {};

        converted[mn] = covmat;

        for (var prop in mat) {

          var save = true;
          var value = mat[prop];
          var lprop = prop.toLowerCase();

          switch (lprop) {

            case 'kd':
            case 'ka':
            case 'ks':

              // Diffuse color (color under white light) using RGB values

              if (this.options && this.options.normalizeRGB) {

                value = [value[0] / 255, value[1] / 255, value[2] / 255];

              }

              if (this.options && this.options.ignoreZeroRGBs) {

                if (value[0] === 0 && value[1] === 0 && value[2] === 0) {

                  // ignore

                  save = false;

                }

              }

              break;

            default:

              break;

          }

          if (save) {

            covmat[lprop] = value;

          }

        }

      }

      return converted;

    },

    preload: function () {

      for (var mn in this.materialsInfo) {

        this.create(mn);

      }

    },

    getIndex: function (materialName) {

      return this.nameLookup[materialName];

    },

    getAsArray: function () {

      var index = 0;

      for (var mn in this.materialsInfo) {

        this.materialsArray[index] = this.create(mn);
        this.nameLookup[mn] = index;
        index++;

      }

      return this.materialsArray;

    },

    create: function (materialName) {

      if (this.materials[materialName] === undefined) {

        this.createMaterial_(materialName);

      }

      return this.materials[materialName];

    },

    createMaterial_: function (materialName) {

      // Create material

      var scope = this;
      var mat = this.materialsInfo[materialName];
      var params = {

        name: materialName,
        side: this.side

      };

      function resolveURL(baseUrl, url) {

        if (typeof url !== 'string' || url === '')
          return '';

        // Absolute URL
        if (/^https?:\/\//i.test(url)) return url;

        return baseUrl + url;

      }

      function setMapForType(mapType, value) {

        if (params[mapType]) return; // Keep the first encountered texture

        var texParams = scope.getTextureParams(value, params);
        var map = scope.loadTexture(resolveURL(scope.baseUrl, texParams.url));

        map.repeat.copy(texParams.scale);
        map.offset.copy(texParams.offset);

        map.wrapS = scope.wrap;
        map.wrapT = scope.wrap;

        params[mapType] = map;

      }

      for (var prop in mat) {

        var value = mat[prop];
        var n;

        if (value === '') continue;

        switch (prop.toLowerCase()) {

          // Ns is material specular exponent

          case 'kd':

            // Diffuse color (color under white light) using RGB values

            params.color = new THREE.Color().fromArray(value);

            break;

          case 'ks':

            // Specular color (color when light is reflected from shiny surface) using RGB values
            params.specular = new THREE.Color().fromArray(value);

            break;

          case 'ke':

            // Emissive using RGB values
            params.emissive = new THREE.Color().fromArray(value);

            break;

          case 'map_kd':

            // Diffuse texture map

            setMapForType("map", value);

            break;

          case 'map_ks':

            // Specular map

            setMapForType("specularMap", value);

            break;

          case 'map_ke':

            // Emissive map

            setMapForType("emissiveMap", value);

            break;

          case 'norm':

            setMapForType("normalMap", value);

            break;

          case 'map_bump':
          case 'bump':

            // Bump texture map

            setMapForType("bumpMap", value);

            break;

          case 'map_d':

            // Alpha map

            setMapForType("alphaMap", value);
            params.transparent = true;

            break;

          case 'ns':

            // The specular exponent (defines the focus of the specular highlight)
            // A high exponent results in a tight, concentrated highlight. Ns values normally range from 0 to 1000.

            params.shininess = parseFloat(value);

            break;

          case 'd':
            n = parseFloat(value);

            if (n < 1) {

              params.opacity = n;
              params.transparent = true;

            }

            break;

          case 'tr':
            n = parseFloat(value);

            if (this.options && this.options.invertTrProperty) n = 1 - n;

            if (n > 0) {

              params.opacity = 1 - n;
              params.transparent = true;

            }

            break;

          default:
            break;

        }

      }

      this.materials[materialName] = new THREE.MeshPhongMaterial(params);
      return this.materials[materialName];

    },

    getTextureParams: function (value, matParams) {

      var texParams = {

        scale: new THREE.Vector2(1, 1),
        offset: new THREE.Vector2(0, 0)

      };

      var items = value.split(/\s+/);
      var pos;

      pos = items.indexOf('-bm');

      if (pos >= 0) {

        matParams.bumpScale = parseFloat(items[pos + 1]);
        items.splice(pos, 2);

      }

      pos = items.indexOf('-s');

      if (pos >= 0) {

        texParams.scale.set(parseFloat(items[pos + 1]), parseFloat(items[pos + 2]));
        items.splice(pos, 4); // we expect 3 parameters here!

      }

      pos = items.indexOf('-o');

      if (pos >= 0) {

        texParams.offset.set(parseFloat(items[pos + 1]), parseFloat(items[pos + 2]));
        items.splice(pos, 4); // we expect 3 parameters here!

      }

      texParams.url = items.join(' ').trim();
      return texParams;

    },

    loadTexture: function (url, mapping, onLoad, onProgress, onError) {

      var texture;
      var manager = (this.manager !== undefined) ? this.manager : THREE.DefaultLoadingManager;
      var loader = manager.getHandler(url);

      if (loader === null) {

        loader = new THREE.TextureLoader(manager);

      }

      if (loader.setCrossOrigin) loader.setCrossOrigin(this.crossOrigin);
      texture = loader.load(url, onLoad, onProgress, onError);

      if (mapping !== undefined) texture.mapping = mapping;

      return texture;

    }

  };
  return MTLLoader;

}